This invention relates to a communications network for general purpose data communications in a heterogeneous environment.
Recently, there has been a trend towards interconnecting a large, heterogeneous group of computers, batch terminals, and conversational terminals to form a general purpose network of computing resources. For instance, the computing resources of many governmental agencies and universities consist of a large variety of computers supporting a diverse user population with many different applications. Increasingly, these applications have come to require the resources of more than one computer. This has resulted in the direct point-to-point connection of rather large subsets of computers. As this type of network continues to grow, however, the communications plant must expand exponentially and the manpower required to modify existing computer operating systems to resolve differences in character sets and protocol becomes prohibitive.
In addition, data bases have become distributed resulting in enormous quantities of magnetic tape being hand-carried between machines where no point-to-point connections exist. The bandwidth of a cart full of tapes is impressive until one considers the amount of useful data on each tape in contrast to the time it takes to pull these tapes together and then disperse them.
Moreover, there is a growing use of terminals for remote job entry, and interactive processing poses additional problems. Often several terminals sit side by side when one would be sufficient. Unfortunately, each has been designed or programmed for only one manufacturer's computer. A similar situation occurs when the computers are the same, but no mechanism exists for switching a terminal between them.
Therefore, it is a primary object of this invention to provide a modular data communications network for interconnecting many different kinds of processors, terminals, and even other types of communications networks.
It is another object of the present invention to provide a modular data communications network which can accommodate a variety of data transfers, such as large file transfers and highly interactive transfers.